The pulse oximetry via SpO2 sensor technology with non-invasive technique for the continuous measurement of arterial oxygen saturation of the blood has already been well established in the field of patient monitoring. Here, a distinction is made between disposable SpO2 sensors for single use and reusable SpO2 sensors for repeated use.
A disposable SpO2 sensor is in particular used for the continuous observation or long-term monitoring of patients that have to be monitored over several hours, more particularly over several days to ensure maintenance of a healthy state. In use, the disposable SpO2 sensor is applied onto predetermined positions at the body and fixed. After a certain utilization period, as a rule after eight hours, this sensor has to be newly applied to another place of the body. The background to this is to ensure that the sensor does not cause and exercise any negative effects such as undue pressure, temperature, or allergic reactions on this place of body. In addition, in case of reapplication, there is also ensured that the medical skilled person will check that the sensor is functioning properly. An essential advantage of disposable sensors over reusable sensors is given by their construction and fixation to the human body.
The disposable sensor is characterized by its low mass and by the plaster tape material, which at the same time also presents a cost-effective technical variation. Hereby, motion artifacts and hence measuring errors in the patient monitoring at the SpO2 monitor are reduced or excluded, respectively. These are the essential requirements that are necessary for the employment of sensors with newborns and neonates. As many neonates have to be monitored after their birth over several hours, e.g., up to 72 hours, to ensure proper lung function, the employment of an SpO2 disposable sensor is absolutely imperative.
A typical application of the disposable SpO2 sensor involves attachment to the hand or foot of a baby. Since the baby is moving all the time during the period of monitoring, a safe and strong application of the sensor is necessary. The sensor must not slip off from the site of application, from the foot or from the hand, by itself.
Furthermore, it has to be ensured that the SpO2 sensor does not pose a threat to the patient. For example, there could be caused burns at the baby's skin as well as pressure sores of the sensor by a too tight application or allergic reactions by the adhesive material of the plaster tapes at the skin surface.
Therefore, an international norm does exist, the ISO 9919, for all SpO2 monitors and the corresponding SpO2 sensors. Herein, the exact demands on each sensor, and monitor manufacturer are defined also with respect to the sensor's safety requirements.
From the company DIXTAL Medical Inc. (U.S. Pat. No. 6,073,038; U.S. Pat. No. 6,149,481; U.S. Pat. No. 5,891,026), the construction and employment of a neonate pediatric SpO2 sensor is known. Such sensors are characterized by a foam wrap base material, onto which are fixed, by two additional adhesive tapes, a cable and the SpO2 optics soldered thereto composing of SpO2 LEDs and a detector. Generally, the optics and the cable are fixed between two very thin adhesive tapes, which are arranged on the upper side of the fixing strap. Essential disadvantages of such a sensor are:                insufficient fixation of the optics and the cable between the two thin adhesive tapes, wherein there is a risk that mechanical stress, such as pulling the cable when the sensor is applied, may result in the cable together with the optics being pulled out of the disposable sensor;        lack of strain relief by the cable at the sensor, such that moving the cable may result in its release from between the two adhesive tapes;        insufficient protection of the optics and the electric contacts such as cable and stranded wires against penetration of liquids in accordance with the requirements by the norm;        insufficient resistance to movement, wherein the sensor can not be sufficiently fixed at the body, since the thin adhesive tape that holds the optics has insufficient skid resisting properties;        insufficient padding of the sensor against pressure sores at the positions where the optics are located, with the optics separated from the baby's skin by only a very slim tape;        insufficient protection of said sensor from contact discharge, wherein high voltage is not given at a prescribed dielectric strength of 4 kV, since the insulation takes place by only a thin film.        